Paperweight

Handles Paperclip attachments on the backend in a delayed process.

Add this line to your application's Gemfile:

gem 'paperweight'

And then execute:

$ bundle

Or install it yourself as:

$ gem install paperweight

Configure Paperclip as you normally would, according to their docs. Then, add an additional *_processing string field to the model for which you want to process attachments in the background, where * is the name of the attachment that you specified in your model's call to has_attached_file.

class AddImageProcessingToPosts < ActiveRecord::Migration[5.2]
  def change
    add_column :posts, :image_processing, :string
  end
end

This column will be used to hold the temporary URL of the image that needs to be processed. It will override all calls to the #url method on Paperclip attachments until the processing is done so that there's no break in the visibility of the image.

Then, add the ability to update the *_url attribute from the controller.

class PostsController < ApplicationController
  # PUT|PATCH /posts/:id
  def update
    post = Post.find(params[:id])

    if post.update(post_params)
      render json: post
    else
      render error: post.error, status: :unprocessable_entity
    end
  end

  private

  def post_params
    params.permit(:image_url)
  end
end

From now on, updating this attribute will queue a job in the background to update the image later.

You can provide additional configuration options through the Paperweight.configure method, as in:

Paperweight.configure do |config|
  config.download_attempts = 10
  config.max_size = 20 * 1024 * 1024
end

The current configuration options include:

• download_attempts - defaults to 1
• max_size - defaults to 10 MB

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/CultureHQ/paperweight.

The gem is available as open source under the terms of the MIT License.